Modelling aeronautical composite laminates behaviour under impact using a saturation damage and delamination continuous material model

We show that the behavior of T700/M21s and T800/M21s composite panels are affected by the influence of strain rates together with local shear and crush punch or global flexural strengths of the structure. A deterministic continuous composite material model has been developed as a LS-DYNA user defined material model for unidirectional composites on the basis of the Matzenmiller model widely used for woven composites. Initiation and evolution up to saturation and fracture are implemented for various and coupled damage mechanisms including delamination. Quasi-static and dynamic characterization tests laminates have been carried out on balanced angle ply [±θ] and used for calibration of numerical values. Impact induced damage from experiment's measures and numerical predictions are compared for T800/M21S aeronautical samples impacted at 15J

Random Forests: some methodological insights

This paper examines from an experimental perspective random forests, the increasingly used statistical method for classification and regression problems introduced by Leo Breiman in 2001. It first aims at confirming, known but sparse, advice for using random forests and at proposing some complementary remarks for both standard problems as well as high dimensional ones for which the number of variables hugely exceeds the sample size. But the main contribution of this paper is twofold: to provide some insights about the behavior of the variable importance index based on random forests and in addition, to propose to investigate two classical issues of variable selection. The first one is to find important variables for interpretation and the second one is more restrictive and try to design a good prediction model. The strategy involves a ranking of explanatory variables using the random forests score of importance and a stepwise ascending variable introduction strategy

How to promote informal learning in the workplace? The need for incremental design methods

Informal Learning in the Workplace (ILW) is ensured by the everyday work activities in which workers are engaged. It accounts for over 75 per cent of learning in the workplace. Enterprise Social Media (ESM) are increasingly used as informal learning environments. According to the results of an implementation we have conducted in real context, we show that ESM are appropriate to promote ILW. Nevertheless, social aspects must be reconsidered to address users' needs regarding content and access, quality information indicators, moderation and control

Dynamic delamination of aeronautic structural composites by using cohesive finite elements

Cohesive finite elements are used to model impact induced delamination prediction of T800/21M unidirectional laminated composite. DCB, ELS and MMB tests are used to identify cohesive element parameters. Results from experiments and numerical prediction of impact induced delamination by commercially available code LS-DYNA are compared

Simulation of dynamic delamination and mode I energy dissipation

Delamination initiation and propagation of aeronautic composites is an active field of research. In this paper we present a methodology for critical energy release rate correlation of numerical simulation and experimental data. Experiments of mode I critical energy release rate were carried out at quasi static and pseudo dynamic loading rates. Cohesive finite elements are used to predict the propagation of delamination in a carbon fiber and epoxy resin composite material. A bilinear material model is implemented via user defined cohesive material subroutine in LS-DYNA. The influence of mode I energy release rate in mixed mode loading, due to a low velocity impact, is also investigate

A new approach of high speed cutting modelling: SPH method

The purpose of this study is to introduce a new approach of high speed cutting numerical modelling. A lagrangian Smoothed Particle Hydrodynamics (SPH) based model is carried out using the Ls-Dyna software. SPH is a meshless method, thus large material distortions that occur in the cutting problem are easily managed and SPH contact control permits a “natural” workpiece/chip separation. Estimated chip morphology and cutting forces are compared to machining dedicated code results and experimental data. The developed SPH model proved its ability to account for continuous and shear localized chip formation and also correctly estimates the cutting forces, as illustrated in some orthogonal cutting examples

Implementing a forensic educational package for registered nurses in two emergency departments in Western Australia

The results of violence are a major public health problem that infiltrates hospital emergency departments (ED) daily. Often, ED nurses are the first healthcare professionals to see patients, speak with family members, handle personal property and collect laboratory specimens. Such actions can be of extreme importance to the 27 different categories of forensic patients. To adequately address forensic patient issues, ED nurses need exposure to forensic education. The aim of this research was to develop and evaluate the effectiveness of a clinical forensic education package on ED nurses’ perceptions, knowledge and care of forensic patients. To accomplish this aim, this descriptive research study employed a multiple triangulation methodology design. Additionally, theoretical guidance was sought from Bandura’s (1977) Social Cognitive Theory, Malcolm Knowles (1980) Adult Learning Principles and Lynch’s (1990) forensic nursing integrated practice model. Forty nine treatment and control group nursing participants were recruited from two metropolitan Western Australian hospitals. In addition, 22 forensic and hospital stakeholders from 10 specialty areas were interviewed to explore and identify key forensic issues that confront Western Australian healthcare and forensic professionals. Data was obtained from qualitative and quantitative means which included; semi-structured interviews, policy manual reviews, audits of nursing documentation, pre and post-test questionnaires, focus group interviews, and the researcher’s observations. Data analysis indicated that the forensic educational package significantly increased participant’s forensic nursing knowledge by 23.8%. In addition, data indicated that treatment group participants altered their documentation and clinical practices as a result of attending the forensic intervention workshops. The study results suggest that a nurse focused approach can be an effective strategy to address the complex issues violence brings into the healthcare system by improving forensic knowledge, influencing nursing practice, and altering participant perceptions regarding forensic patient care. Moreover, this study identified gaps in the amount and variety of available forensic educational material for nurses. As a result, a clinical forensic nursing self directed learning package was developed which aimed at fulfilling general forensic educational needs for all Registered Nurses across Australia and International settings